1. Field of the Invention
The present invention is directed to connectivity testing of a high speed interface.
2. Description of the Related Art
An important goal of computing device manufacture testing is determining the cause of a printed circuit board (PCB) malfunction. For example, a PCB may malfunction due to a defective integrated circuit (IC) or defective soldering between the IC and a PCB. This can be a very important distinction when the IC is manufactured by one entity and assembled to a PCB by another. A defective soldering job can fixed relatively quickly at little cost by re-soldering. A PCB with a defective IC can be fixed by replacing the IC. Replacing a defective IC is more costly than re-soldering. A PCB soldering malfunction misdiagnosed as a defective IC will increase the cost of manufacturing. Thus, it is important to distinguish between causes of PCB malfunction during manufacturing testing. In particular, distinguishing between defective ICs and defective soldering allows faster debug and repair rates, provides for removal and damage of fewer good parts, and cheaper manufacturing costs.
PCI-Express is high speed interface for transferring data and information between two or more ICs. PCI-Express utilizes AC-coupling and differential signaling to send and receive information. IEEE 1149.1 describes a common boundary scan technology for performing manufacturing tests on some types of ICs. Boundary scan technology detects and asserts signals and data applied to the extruding pins and/or solder balls an IC. The 1149.1 boundary scan technique is not suitable for testing the AC-coupling and differential signaling utilized in PCI-Express. A new technology, IEEE 1149.6, provides for boundary scan testing of AC-coupled and/or differential buses. Though the IEEE 1149.6 can apply and retrieve signals from IC pins utilizing a high speed interface with AC-coupling and differential signaling, its recent release has resulted in limited utilization.
Due to the lack of PCB manufacturing testing capabilities on high speed serial interfaces such as PCI-Express, the cause of PCB malfunction in computing devices utilizing high speed interfaces cannot be distinguished. It is very important to determine whether a PCB malfunction for a high speed interface is caused by a defective IC or defective soldering between the IC and a PCB.